Bi2O3 Surface Research Articles

A Schottky/Z-Scheme Hybrid for Augmented Photocatalytic H2 and H2O2 Production.

The prodigious employment of fossil fuels to conquer the global energy demand is becoming a dreadful threat to the human society. This predicament is appealing for a potent photocatalyst that can generate alternate energy sources via solar to chemical energy conversion. With this interest, we have fabricated a ternary heterostructure of Ti3C2 nanosheet modified g-C3N4/Bi2O3 (MCNRBO) Z-scheme photocatalyst through self-assembly process. The morphological analysis clearly evidenced the close interfacial interaction between g-C3N4 nanorod, Bi2O3 and Ti3C2 nanosheets. The oxygen vacancy created on Bi2O3 surface, as suggested by XPS and EPR analysis, supported the Z-scheme heterojunction formation between g-C3N4 nanorod and Bi2O3 nanosheets. The collaborative effect of Z-scheme and Schottky junction significantly reduced charge transfer resistance promoting separation efficiency of excitons as indicated from PL and EIS analysis. The potential of MCNRBO towards photocatalytic application was investigated by H2O2 and H2 evolution reaction. A superior photocatalytic H2O2 and H2 production rate for MCNRBO is observed, which are respectively around 5 and 18 folds higher as compared to pristine CNR nanorod. The present work encourages for the development of a noble, eco-benign and immensely efficient dual heterojunction based photocatalyst, which can acts as saviour of human society from energy crisis.

Boosting and stabilizing the electrocatalytic reduction of carbon dioxide on Bi2O2CO3 via surface modification with p-aminobenzoic acid

In the realm of electrocatalytic CO2 reduction (ECR) reactions, the challenges of instability and self-reducibility present significant obstacles to the practical application of bismuth oxide-based catalysts. Herein, Bi2O3 pre-catalyst was synthesized and surface-modified with 4-aminobenzoic acid (PABA). Theoretical studies confirmed that PABA was effectively grafted through oxygen vacancies on the Bi2O3 surface, leading to electronic rearrangement. PABA efficiently prevented surface Bi3+ on Bi2O3 from self-reducing to Bi0 during the ECR reaction. The Bi2O3PABA pre-catalyst transformed into the active Bi2O2CO3PABA ECR catalyst via electrolyte mediation. A Faraday efficiency of 98.6 % for formate was achieved at −1.1 V vs. RHE, with a wide potential window of 800 mV. The current density reached 210 mA cm–2 in a 2×2 cm2 flow cell system. Theoretical calculations illustrate that PABA facilitates stabilizing the *OCHO intermediate, diminishing the adsorption barrier. These results may provide valuable insights for designing highly selective ECR catalysts through interface engineering.

Enhancing photocatalytic degradation of rhodamine B with visible-light-driven HCl-assisted Bi2O3 photocatalysts: Activity, mechanism, and pathways

This study utilized X-diffraction, BET, photoluminescence, UV–vis DRS, FTIR, SEM, XPS, TOC analysis, EPR, electrochemical measurements, and LC-MS to characterize the structural characteristics, morphology, optical properties, photocatalytic activity, surface electronic states, active compounds, and potential photodegradation pathways of rhodamine B (RhB) over as-prepared Bi2O3. The as-prepared Bi2O3 photocatalyst exhibited a narrow bandgap, which enabled efficient absorption of visible light, thereby contributing to its enhanced photocatalytic activity. Additionally, Bi2O3 exhibited a high degradation efficiency for RhB. with up to 96.8 % of RhB removed within 120 min at pH 3.0. The excellent photocatalytic performance of Bi2O3 can be attributed to the formation of the heterogeneous Bi2O3/BiOCl structure on the Bi2O3 surface in the presence of HCl. Moreover, the TOC analysis revealed that over 58.1 % of the carbon in the RhB solution was mineralized into CO2 after 120 min of irradiation. The effect of catalyst content, RhB concentration, initial pH, and inorganic anions on the photocatalytic degradation of RhB over Bi2O3 was examined. Furthermore, the active compounds and potential photocatalytic mechanism of the Bi2O3/BiOCl heterogeneous structure toward RhB were evaluated. The intermediates formed during RhB degradation were identified, and the corresponding degradation pathway was deduced via LC-MS.

In Situ Growth of CuBi2O4/Bi2O3 Z-Scheme Heterostructures for Bifunctional Photocatalytic Applications.

In this study, we present an in situ solvothermal approach for synthesizing a highly efficient bifunctional CuBi2O4/Bi2O3 composite catalyst for applications in H2 production and the removal of organic pollutants. Various characterization techniques, including XRD, UV-vis DRS, SEM, TEM, and EIS, were used to characterize the prepared catalyst. Density functional theory calculations confirmed a Z-scheme mechanism, revealing the charge transfer mechanism from the Bi2O3 surface to the CuBi2O4 surface. The composite exhibited a photocurrent of 2.83 × 104 A/cm2 and a hydrogen production rate of 526 μmolg-1h-1 under natural sunlight. Moreover, the catalyst demonstrated efficient degradation of RhB up to 58% in 120 min under 50 W LED illumination. Additionally, multiple recycling tests confirmed its high stability and recyclability, making it a promising candidate for various applications in the field of photocatalysis.

Combining heterointerface/surface oxygen vacancies engineering of bismuth oxide to synergistically improve its solar water splitting performance

Solar-powered photoelectrochemical (PEC) water splitting is recognized as a strategy for addressing fossil resource and global warming concerns. The purpose of this paper is to demonstrate for the first time a facile method to fabricate dendritic nanostructured (DN) Bi:Bi2O3 heterointerface engineering junctions that possess abundant surface oxygen vacancies (OVs, DN Bi:Bi2O3-OVs/FTO), with outstanding PEC performance. The surface OVs serve as shallow donors and active reaction sites, whereas the Bi-metal bridges are used for fast electron transport. Furthermore, surface OVs can enhance the surface features of Bi:Bi2O3 heterointerfaces and boost their electrical conductivity and donor density. This greatly enhances electrolyte ion and electron mobility, resulting in rapid water oxidation reactions at the Bi:Bi2O3/electrolyte interfaces. By combining the Bi:Bi2O3 heterointerface junction and surface OVs, we are able to create an effective photoanode with 95 % charge injection efficiency, applied bias photon-to-current efficiency (ABPE) of 0.112 %, and a photocurrent response of 0.334 mA.cm−2 at 1.23 V vs. the reversible hydrogen electrode (RHE), which represents improvements of about 4.5 and 10 folds over that of pure DN Bi2O3 photoanode. It is possible to construct a variety of unique nanostructured electrodes with adjustable optical and electronic properties to be used in solar cells, energy storage, and PEC applications.

Mechanistic insights for electroreduction of CO2 on pristine monoclinic α-Bi2O3 (120) surface

To date, the electrochemical reduction of CO2 (CO2RR) into valuable chemicals is a promising method for combating global warming. However, finding a suitable electrocatalyst for CO2RR is critical to reducing CO2 emissions. Herein, the CO2RR mechanism on a pristine monoclinic Bi2O3 (120) surface was thoroughly investigated using density-functional theory (DFT) calculations. The CO2 adsorption modes of side-on, end-on, and chemisorbed were compared, with the chemisorbed species outperforming for CO2 activation. Furthermore, analyses of the Bader charge, the density of states, and electron density difference strongly suggest that the Bi2O3 (120) surface has excellent activation for CO2 molecules. More importantly, the DFT calculations revealed that the electrochemical CO2RR over the Bi2O3 surface favors both formic acid and methanol in the limiting-potential step of *CO2→ *COOH with the free energy barriers of 0.86 eV and 0.87 eV with and without solvent, respectively. The microkinetic simulation also supports the DFT result, showing the possibility of more selective production by predicting desorption temperatures. This research suggests a promising way for CO2RR mechanisms on pristine monoclinic Bi2O3 surfaces to produce formic acid (HCOOH) and methanol (CH3OH).

Preparation of Z-scheme Au-Ag2S/Bi2O3 composite by selective deposition method and its improved photocatalytic degradation and reduction activity

In this work, Z-scheme Ag2S/Bi2O3 composites were fabricated through the precipitation of Ag2S nanoplates on the surface of Bi2O3 microrods. Consequently, Au nanoparticles were selectively deposited on the Ag2S nanoplates surface to obtain.Au-Ag2S/Bi2O3 composites using near-infrared light photodeposition method. The characterization results indicate that the Ag2S nanoplates were uniformly anchored on Bi2O3 surface, and Au nanoparticles were highly dispersed on the surface of Ag2S nanoplate instead of Bi2O3. Acid orange 7 (AO7), Rhodamine B (RhB) and Cr(VI) were chosen as model reactant for the evaluation of photocatalytic degradation and reduction activity of the products under simulated sunlight irradiation. After the decoration of Ag2S nanoplates, the photocatalytic activity of Ag2S/Bi2O3 is much higher than that of bare Bi2O3, and the optimal catalytic efficiency is achieved by 12 %Ag2S/Bi2O3 sample. More importantly, the photocatalytic activity of 12 %Ag2S/Bi2O3 sample can be further enhanced by the selective decoration Au nanoparticles on the Ag2S nanoplates. Among the ternary composites, 2Au-12 %Ag2S/Bi2O3 sample with the Au content of 2% exhibits highest catalytic efficiency for 60 min (AO7: 96%; RhB: 56%; Cr(VI): 65%). The possible mechanism for the improvement of the photocatalytic activity of Bi2O3 by Ag2S and Au decoration was proposed.

Improved photocatalytic degradation and reduction performance of Bi2O3 by the decoration of AuPt alloy nanoparticles

Abstract In this work, AuPt alloy nanoparticles were attached onto the surface of Bi2O3 particles to obtain AuPt/Bi2O3 composite. The existence of AuPt bimetallic alloy and their homogeneous distribution on Bi2O3 surface were fully confirmed by XPS characterization and HRTEM observation. The surface plasmon resonance (SPR) effect of noble metals was detected using Ultraviolet–visible diffuse reflectance spectra. The photocatalytic degradation and reduction ability of products were estimated using Acid orange 7 (AO7), phenol and Cr(VI) as the target reactant under simulated sunlight irradiation, indicating that AuPt/Bi2O3 composite possesses remarkable higher photocatalytic activity compared with bare, Au and Pt decorated Bi2O3. In addition, AuPt/Bi2O3 composite is proved to be a stable photocatalysts. The effective separation and migration of photoinduced electrons and holes in AuPt/Bi2O3 sample is demonstrated employing electrochemical and photoluminescence detection. The AuPt/Bi2O3 composite not only has suitable schottky barrier height for trapping the photogenerated charges but also exhibits surface plasmon resonance (SPR) effect, which leads to enhanced photocatalytic activity.

A novel and facile procedure to decorate Bi2O3 with Bi2S3 nanocrystals: Composites synthesis, analyses, and photocatalytic performance assessment

In the current investigation, a novel and in-situ sulfurization protocol was utilized in pure carbon disulfide (CS2) to successfully establish binary composites Bi2S3-Bi2O3 at room temperature. These composites were systematically analyzed for relevant microstructures and morphology. The existence of in-situ produced Bi2S3 in composites was confirmed by UV–vis diffuse reflectance spectra, X-ray photoelectron spectra, Fourier transform infrared spectra, and elemental mapping images. In addition, the resultant Bi2S3 species were formed as nanocrystals embellished on Bi2O3 surface to generate heterojunction structures. These achieved composites exhibited heightened photocatalytic degradation performance over Rhodamine B (RhB) and methyl orange (MO) in comparison to bare Bi2S3 and Bi2O3 under visible light, mainly attributing to suitable phase composition, strengthened visible-light absorption, and formation of heterojunction structures, by which abundant charge carriers were generated and spatially separated. In addition, these composites possessed satisfactory reusability and structural stability and a plausible type-II photocatalytic mechanism was eventually conjectured basing on band structures of both components and relevant experiments.

A new analytical method based on bismuth oxide-fullerene nanoparticles and photocatalytic oxidation technique for toluene removal from workplace air

A new sorbent based on mixture of bismuth oxide-fullerene nanoparticles (Bi2O3-NF) was used for degradation/removal of toluene from workplace and artificial air by UV-photocatalytic oxidation method (UV-PCOM). By set up of pilot, standard gas of toluene was generated with difference concentrations, and then was passed through UV lamp-glass quartz cell accessory(UV-GQC) by SKC pump at optimized flow rate. Following the UV irradiation, the electrons and holes can undergo redox reactions with toluene on the Bi2O3 surface that lead to the formation of toluene intermediates and toluene. Toluene and intermediates was physically and radically absorbed on the 200 mg of NF at room temperature and then, desorbed from it at 185 OC before determined by GC/FID. In optimized conditions, the adsorption capacity and removal efficiency of NF were obtained 212 mg g-1 and more than 95%, respectively.

A newly constructed photoactive system, Fe(III)-C/N-Bi2O3, for efficient visible light photocatalysis

In this study, two strategies are simultaneously applied for photocatalytic activity enhancement of Bi2O3. The first strategy is to increase the light absorption via simultaneous carbon and nitrogen doping. The second strategy is to increase the charge carrier separation via Fe grafting. Transmission electron microscopy observation reveals the presence of Fe nanoclusters resided on the Bi2O3 surface. Near edge X-ray absorption fine structure (NEXAFS) analysis confirms the valence state of the Fe species to be +3, and their coordination to be octahedral. The C K-edge and N K-edge NEXAFS spectra furthermore confirm the incorporation of C and N species in the Bi2O3 structure. This newly constructed photocatalyst, denoted as Fe(III)-C/N-Bi2O3, shows appreciably enhanced photocatalytic performance for the decomposition of 2,4-dichlorophenol under visible light as compared to bare Bi2O3.

Cu(II)/Bi2O3 Photocatalysis for Toxicity Reduction of Atrazine in Water Environment under Different Light Wavelengths

Cu(II)/Bi2O3 photocatalyst was successfully synthesized through a simple sol-gel route. The photocatalyst was characterized by synchrotron-based techniques including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), and other techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS). Its photocatalytic activity was evaluated for degradation and mineralization of atrazine in aqueous solutions under different light wavelengths (visible, UVA, UVB and UVC). The toxicity of photocatalytically treated atrazine solution was comprehensively tested by nine different bioassays. Results show that Cu species on the Bi2O3 surface exists in +2 oxidation state, which is coordinated with four O atoms with an average bond length of 1.947 A. The light wavelength was found to affect the final toxicity of atrazine solution. Irradiation of Cu(II)/Bi2O3 with visible light generally resulted in lower toxicity of atrazine solution although it led to slower degradation and mineralization of atrazine. Therefore, as far as the toxicity reduction is concerned, use of visible light for Cu(II)/Bi2O3 is preferred. Based on the present findings, proper selection of light wavelength could be a suitable option for toxicity reduction of photocatalyically treated organic contaminants in water environment.

Bi2O3 as a Promoter for Cu/TiO2 Photocatalysts for the Selective Conversion of Carbon Dioxide into Methane

AbstractA significantly enhanced gas‐phase photocatalytic conversion of carbon dioxide into methane on Cu/TiO2 nanoparticles upon introducing Bi2O3 as a promoter in the vicinity of Cu was observed. The maximum rate of CH4 generation of 11.90 μmol g−1 h−1 recorded in the case of Cu‐Bi2O3/TiO2 is approximately one order of magnitude higher than that obtained with Cu/TiO2 nanoparticles. The enhanced performance was attributed to facilitated migration of CO* from Cu to the Bi2O3 surface.

Catalytic Deposition of ZnO on Bi2O3 Surface Towards Prolonged Zn-Based Aqueous Rechargeable Battery

Recently, the demand for the large-scale power system has gained much interest due to the increase in energy demand. Scientists recognize load leveling as one of the most crucial aspect in making efficient large-scale power generation. Electrical energy storage (EES) system is most promising type of energy storage systems. Among number of criteria for the large-scale EES, low cost is one of the main focus. To achieve low cost of EES, Zn based aqueous battery should be utilized in the EES, due to the abundance and low cost of Zn and water. However, Zn based aqueous battery suffers from an intrinsic problem. When the Zn is oxidized to ZnO, Zn(OH)4 -2 ion, intermediate phase is formed. This ion is soluble in aqueous electrolyte. When Zn is oxidized, most of the Zn2+ ion detaches from the current collector becoming inactive in the electrochemical process and the battery becomes non-rechargeable. There is a large number reports using Zn electrode in an electrochemical cell. Among them, numerous reports have suggested the use of Bi2O3 as an electrode additive. By simply mixing in the Bi2O3 to the Zn electrode, the electrochemical performance suddenly improves. Thus far in the literature, most explanation for such a phenomenon is improvement in the electrical conductivity. Due to the presence of Bi2O3, a better electrical connection is formed and thus the electrochemical performance is improved. However, electrical conductivity does not have an effect on the intrinsic chemical reaction of Zn oxidation. Here, we have conducted a series of characterizations to understand the mechanistic role of Bi2O3 in the Zn electrode. We have utilized electrochemistry, energy-dispersive X-ray spectroscopy mapping under scanning electron microscope, powder X-ray diffraction (PXRD), Raman spectroscopy, and X-ray photoelectron spectroscopy. Upon oxidizing the Zn electrode, the Bi2O3 surface was covered with ZnO. This ZnO had interactions with the Bi2O3 which was found in PXRD and Raman spectroscopy. We have discovered that the mechanism for the improved performance in the Zn based electrode with the presence of Bi2O3 is due to a surface catalytic deposition of ZnO. With the presence of Bi2O3, Zn oxidation reaction seems to skip the soluble Zn(OH)4 -2 phase formation and directly deposits ZnO onto the surface of Bi2O3. This finding open the way for further optimizing the Zn based electrodes for rechargeable aqueous batteries

Size-controllable synthesis of Bi/Bi2O3 heterojunction nanoparticles using pulsed Nd:YAG laser deposition and metal-semiconductor-heterojunction-assisted photoluminescence.

We synthesized Bi/Bi2O3 heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi2O3 heterojunction nanoparticles consisted of Bi nanoparticles and Bi2O3 surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi2O3 surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi2O3 surface layers, which are the metal-semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi2O3 nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi2O3 surface layers. The enhancement of PL emission at room temperature by metal-semiconductor-heterojunctions make the Bi/Bi2O3 heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes (LEDs) and laser diodes (LDs).

Nanodiamond for tuning the properties of energetic composites

Bismuth oxide (Bi2O3) particles were coated by detonation nanodiamonds. The resulting nanocomposite materials were mixed with an aluminum nanopowder (≈100nm) to prepare nanothermites, with reduced sensitivity to friction and electrostatic discharge (ESD). The use of nanodiamond for this purpose is reported here for the first time. Their numerous qualities such as their small size, antifriction properties and thermal conductivity make them ideal candidates. Small amounts of detonation nanodiamonds allow obtaining impressive desensitization, making thus modified Bi2O3/Al nanothermite safe to handle. A composition containing around 1wt.% of nanodiamond has a sensitivity threshold to friction superior to 100N instead of 5N for the thermite without nanodiamond. Furthermore, the sensitivity threshold to electrostatic discharge increases to 20 times when the nanodiamond content reaches 1.8wt.%. The antifriction properties of nanodiamond limit the scratching of Bi2O3 surface by Al particles. The desensitization to ESD is observed for a sufficient coverage of the oxide particles (1.8wt.% of ND), which restrains the effect of the melt dispersion mechanism of aluminum and prevents the mixing of the oxidizing and the reducing parts of the composites. A good reactivity of the thermite could be maintained for nanodiamond content up to 2.6wt.%. The carburizing of aluminum coming on contact with nanodiamond during the thermite reaction could be evidenced by X-ray Diffraction and calorimetry measurements and also participates to the desensitization of the nanothermite. This kind of desensitization by using detonation nanodiamond can also be applied to other nanothermites having low sensitivity threshold to friction and ESD.

Insights into hydrogen generation from formic acid on PtRuBiOx in aqueous solution at room temperature

The catalytic dehydrogenation of formic acid (HCOOH) on heterogeneous catalysts in aqueous solution to produce CO-free H2 has received intense investigation due to its promising application in portable power devices. In this work, we present a study on the mechanism of HCOOH dehydrogenation on the PtRuBiOx catalyst using density functional theory (DFT) calculations supported by complementary experiments. The catalyst's activity at room temperature was clarified by investigating HCOOH dehydrogenation on PtRu alloy and Bi2O3 surface with a focus on the key reaction steps. The PtRu with different alloying degree was modeled by a four-layer p (2 × 2) unit cell with Pt-skin and leaving Ru atoms in the second and the third layer based on the surface energy and the formation energy. The Bi2O3 surface was represented by the most stable (111) surface of δ-Bi2O3. Based on the computational and experimental results, a reaction pathway for HCOOH dehydrogenation on the PtRuBiOx in aqueous solution was proposed. The results suggest that the promotion of HCOOH dissociation on the Bi2O3 surface and the ligand effect between Pt and Ru are responsible for the activity of PtRuBiOx toward HCOOH dehydrogenation in aqueous solution at room temperature. Furthermore, the PdBiOx system was also prepared and investigated as a catalyst for HCOOH decomposition at room temperature. The catalytic behavior of PdBiOx for HCOOH dehydrogenation in aqueous solution was compared with that of the PtRuBiOx.

Radiotracer study of the adsorption of sulfate ions at a Bi2O3 powder/electrolyte solution interface

The pH and concentration dependence of the adsorption of sulfate ions on powdered Bi2O3 was studied by a radiotracer technique in the presence of a large excess of perchlorate supporting electrolyte. It was found that, similar to other oxides such as Al2O3, Cr2O3 and Fe2O3, the extent of adsorption is determined by the protonation of the Bi2O3 surface. The redox transformations of Bi adatom layers are discussed in the light of the results obtained. It is established that for the interpretation of the redox processes occurring at the Bi/electrolyte interface the role of protonation of the oxide formed and the anion adsorption induced by the oxide layer should be taken into consideration.